A transition to a higher degree of integration of semiconductor chips in a modular semiconductor device in which a plurality of semiconductor chips, for example IGBT (Insulated Gate Bipolar Transistors), is accommodated in the same package has recently been advanced. In such a modular semiconductor device, the dimensional accuracy of external terminals joined to a wiring substrate inside the package is therefore required in addition to the joining strength and reliability of the external terminals.
FIG. 13 is a plan view illustrating schematically the conventional modular semiconductor device. FIG. 14 is a cross-sectional view taken along a line AA-AA′ in FIG. 13. FIG. 15 is a cross-sectional view taken along a line BB-BB′ in FIG. 13. As shown in FIGS. 13 to 15, the conventional semiconductor device 100 is provided with semiconductor chips 101, wiring substrates 102, aluminum wires 103, main terminals 104, a control terminal 105, a metal base 106, and a resin case 120. The resin case 120 is obtained by integrally molding a lid 121 and a side wall 122.
In the wiring substrate 102, circuit patterns 102a, 102b are formed on the surface of an insulating substrate. The rear surface of the semiconductor chip 101 is joined by a joining material (not shown in the figure) to the circuit pattern 102a of the wiring substrate 102. An electrode (not shown in the figures) provided on the front surface of the semiconductor chips 101 and the circuit pattern 102b of the wiring substrate 102 are electrically connected to each other by the aluminum wire 103. Further, one end of each of the main terminals 104 and one end of the control terminal 105, which are external terminals, are joined by a joining material 111 to the circuit pattern 102b of the wiring substrate 102.
A metal film 102c is provided on the rear surface of the wiring substrate 102, and this metal film 102c is joined by a joining material (not shown in the figure) to the metal base 106. The metal base 106 is produced from a material with good thermal conductivity and conducts the heat generated by the semiconductor chip 101 and transferred through the wiring substrate 102 to the outside of the semiconductor device 100. The resin case 120 is bonded to the circumferential edge of the metal base 106. The other end of each main terminal 104 and the other end of the control terminal 105 are exposed to the outside of the resin case 120 through the lid 121 of the resin case 120.
A through hole 121a through which the control terminal 105 passes is provided in the lid 121. The through hole 121a has a substantially rectangular planar shape having the dimensions corresponding to the width and thickness of the control terminal 105 molded, for example, from a single plate-shaped member. The width w101 of the through hole 121a in the longitudinal direction thereof has a dimension obtained by adding up a width w111 of a section (referred to hereinbelow as “through section”) 105a of the control terminal 105 that passes through the lid 121 and a width w112 of a protruding section 105d of the below-described through section 105a. The side section of the through hole 121a in the longitudinal direction is parallel to the arrangement direction of the main terminals 104 fixed to the lid 121.
The side section of the through hole 121a in the lateral direction is provided with an L-shaped step 121b on the side of the surface (referred to hereinbelow as “front surface”) of the lid 121 that is exposed to the outside of the resin case 120. A protrusion 121c that protrudes to the wiring substrate 102 side and is connected to the side section of the through hole 121a that faces the side section provided with the step 121b is provided on the surface (referred to hereinbelow as “rear surface”) of the lid 121 that is exposed inside the resin case 120. The control terminal 105 contacts and is locked (fixed) to the step 121b and the protrusion 121c. 
More specifically, the control terminal 105 is constituted by the through section 105a passing through the through hole 121a of the lid 121, a connection section 105c joined to the circuit pattern 102b of the wiring substrate 102, and a linking section 105b that links the through section 105a and the connection section 105c. The through section 105a, the linking section 105b, and the connection section 105c are constituted by plate-shaped members. The other end (referred to hereinbelow as “lower end portion”) of the connection section 105c that is on the side opposite that of the end (referred to hereinbelow as “upper end portion”) linked to the linking section 105b is joined by the joining material 111 to the circuit pattern 102b of the wiring substrate 102.
The flat surface of the connection section 105c is substantially perpendicular to the front surface of the wiring substrate 102. The linking section 105b is linked to the connection section 105c at the connection section 105c on the lid 121 side (upper end portion) and forms an L-shape together with the connection section 105c. The flat surface of the linking section 105b is at a substantially right angle to the flat surface of the connection section 105c and is substantially parallel to the front surface of the wiring substrate 102. Further, the linking section 105b is linked to the end portion (referred to hereinbelow as “lower end portion”) of the through section 105a on the wiring substrate 102 side and forms an L-shape together with the through section 105a. 
The flat surface of the linking section 105b is arranged at a substantially right angle to the flat surface of the through section 105a. The flat surface of the through section 105a is substantially perpendicular to the front surface of the wiring substrate 102. The end portion (referred to hereinbelow as “upper end portion”) on the opposite side with respect to the lower end portion of the through section 105a is exposed to the outside of the resin case 120 from the through hole 121a provided in the lid 121. A protruding section 105d is provided on the side surface of the through section 105a facing the step 121b formed at the side section of the through hole 121a. 
The protruding section 105d is provided with a shape such that is narrow on the upper end portion side of the through section 105a and expands toward the lower end portion side. The lower end portion of the protruding section 105d contacts the bottom surface of the step 121b. The protruding section 105d prevents the control terminal 105 from moving toward the wiring substrate 102. Further, the surface of the linking section 105b on the lid 121 side comes close to the protrusion 121c provided on the rear surface of the lid 121. The linking section 105b thus prevents the control terminal 105 from moving in the withdrawing direction from the wiring substrate 102.
A method for locking the control terminal 105 to the lid 121 will be explained below. FIGS. 16(a)-16(c) are explanatory drawings illustrating the principal part of the conventional semiconductor device in the assembling process. FIGS. 16(a) to 16(c) illustrate a control terminal vicinity 130 in the semiconductor device 100 shown in FIG. 14. FIG. 16(a) shows the control terminal 105 before it is inserted into the through hole 121a. FIG. 16(b) shows the control terminal 105 inserted in the through hole 121a. FIG. 16(c) shows the control terminal 105 locked to the lid 121.
In the semiconductor device 100 that is being manufactured, as shown in FIGS. 16(a) to 16(c), treatment is performed to bond the resin case 120 to the metal base (not shown in the figure). The lower end portion of the connection section 105c of the control terminal 105 is joined to the circuit pattern 102b of the wiring substrate 102 (this joint is not shown in FIGS. 16(a) to 16(c)). First, as shown in FIG. 16(a), the through section 105a of the control terminal 105 is inserted from the rear surface side of the lid 121 into the through hole 121a. 
Then, as shown in FIG. 16(b), the through section 105a is further inserted into the through hole 121a so that a portion of the protruding section 105d of the through section 105a is exposed on the front surface side of the lid 121. Since the width w101 of the through hole 121a in the longitudinal direction has a dimension (w101=w111+w112) obtained by adding up the width w111 of the through section 105a and the width w112 of the protruding section 105d, the portion of the through section 105a where the protruding section 105d is provided also passes through the through hole 121a. 
Then, the through section 105a is inserted into the through hole 121a till the surface of the linking section 105b linked to the lower end portion of the through section 105a, this surface being on the lid 121 side, contacts the protrusion 121c provided on the rear surface of the lid 121. When the surface of the linking section 105b on the lid 121 side contacts the protrusion 121c, the upper end portion of the through section 105a is exposed to the outside of the resin case 120, and the protruding section 105d provided at the through section 105a is exposed inside the step 121b. 
The control terminal 105 is then moved in the direction parallel to the front surface of the lid 121, and the lower end portion of the protruding section 105d contacts the bottom surface of the step 121b, as shown in FIG. 16(c). As a result, the control terminal 105 is prevented by the protruding section 105d and the linking section 105b from moving, and the control terminal 105 is locked to the lid 121.
The following device has been suggested as a modular semiconductor device of an outsert structure in which the control terminal and the resin case are thus separated. The lid is provided with three blocks, and a nut accommodation groove is formed in each of substantially central sections on the upper surface of each block. The blocks are linked together by linking sections, and gaps are formed between the blocks. The gaps are subsequently closed by filling with a sealing resin. A pair of overhang sections is provided on the side surface of the block, and four square holes for inserting and prefixing signal terminals are formed in the overhang sections. A signal terminal is formed in a substantially L-shape from a sheet material, a bulging section is formed somewhat closer to the upper end with respect to the center of the vertical section, and a locking section is formed somewhat closer to the lower end with respect to the center. The bulging section contacts the inner wall of the angular hole and is then forcibly inserted to the position of the locking section, whereby the signal terminal is locked and prevented from falling down (see, for example, Patent Document 1).
The following device of a different configuration has also been suggested. The side surface of a resin case is constituted by a clamping section that extends inward and has an opening in the center, a groove surrounded by the clamping section and provided in the outer wall, and a support base provided below the clamping section and extending inward. An external lead-out terminal is constituted by a cut-out section with a width less than that of the opening of the clamping section, a protruding section protruding toward the side wall side, and a bent section provided below the cut-out section and extending inward. Where the cut-out section of the external lead-out terminal is passed through the opening in the clamping section at the outer wall of the resin case and the external lead-out terminal is lowered, the bent section of the external lead-out terminal is supported by the support base and a catch of the external lead-out terminal is engaged with the groove of the resin case (see, for example, Patent Document 2).
The following device of a different configuration has also been suggested. A locking section for positioning when an external take-out terminal is fixedly attached by soldering is provided at the insulating case itself, and an inclined groove for retaining an adhesive for bonding a heat radiation plate to the insulating case is formed in the lower end surface of the insulating case. An external take-out terminal insertion hole of the insulating case is an angular orifice of a relatively large opening width in part thereof, and the take-out terminal can be tentatively locked by locking the clocking section of the external take-out terminal with a step formed in the section communicating with a small-diameter angular office. Where the external take-out terminal is inserted from the lower angular orifice side and then further inserted against the elastic force acting to induce the outward expansion at the position of the locking section, the locking section expands inside the wide angular orifice while passing through the angular orifice and is restricted and tentatively locked by the step and the inner wall of the wide angular orifice (see, for example, Patent Document 3).    Patent Document 1: Japanese Utility Model Application Publication No. H5-15444    Patent Document 2: Japanese Patent Application Publication No. H7-153906    Patent Document 3: Japanese Patent Application Publication No. H10-65098